Fluid sample testing often involves contacting a test strip with the sample, whereby the test strip contains reactants for one or more analytes. Test strips are commercially available for a variety of analytes such as blood glucose, pH, biomarkers, etc. For instance, a well-known test strip provider is Becton, Dickinson and Company, Franklin Lakes, N.J. Reaction of the analytes with the reactants on the test strip effects a color change that can then be detected using a reader. An example of commercially-available test strip readers includes those from Roche Diagnostics, Indianapolis, Ind.
A drawback to conventional test strip readers is that they are highly subjective and prone to errors. Namely, variations in factors such as sample volume, reaction time, the light source or sources used to illuminate the sample for reading, etc. can all produce a different color reading. Thus, these conventional tests are highly subjective and prone to errors. In fact, when tested against a panel of test strips with known concentrations of analytes, conventional readers produced a significant number of errors.
Another limitation of conventional test strip readers is that they are not sensitive enough to detect small variations in color on the test strips. Thus, commercial readers might return the same result for multiple samples of slightly varying concentration simply because they are not able to resolve the differences in color between the samples.
Further, it has been found that commercial test strip readers produce null results at low analyte concentrations and become saturated at high analyte concentrations. For instance, increasing the analyte concentration beyond a certain amount produces no corresponding change in the color intensity detected by the reader, even though there is a perceptible change in the color of the test strip. Thus, the detection range of commercial readers is quite limited or narrow-range.